The present invention relates to a mask apparatus assisting in the respiratory process, and in particular to an apparatus enabling persons with physiological deficiencies such as cardiac or respiratory ailments to be active in frigid air environments without subjecting their respiratory systems to the stress created by inhaling extremely cold ambient air.
It is well known that the inhalation of air in low temperature surroundings may be burdensome on the human respiratory system, sharply reducing the ability to carry on outside activities efficiently under such conditions. In order to adequately admit oxygen into the body, the frigid ambient air from which it is taken must be warmed sufficiently in the upper respiratory tract. Such a process necessitates a dissipation of a great deal of heat energy, and may result in the initiation of fatigue far more rapidly than in warmer climates. Persons with cardiac problems or respiratory deficiencies are especially susceptible to discomfort and impaired function caused by the inhalation of cold air and may even be subject to intense pain or attacks of angina pectoris as a result. Due to their increased sensitivity to the breathing of frigid air, such persons have often been forced to sharply reduce work and other activities outdoors or forego them altogether.
In recognition of the need for a means of enabling persons with cardiac or respiratory impediments to withstand substantial periods of exposure to air in frigid environments without these difficulties, a number of devices have been developed in the prior art for the purpose of reducing the harmful or dangerous effects caused by the inhalation of extremely cold air. While some of these devices operate to increase air temperature to some degree, they all possess deficiencies rendering them less effective and their use less desirable than that of the present invention.
For example, U.S. Pat. No. 3,491,754 to Weese, U.S. Pat. No. 3,707,966 to Nebel, and U.S. Pat. No. 4,062,359 to Geaghan all disclose devices wherein the body temperature of the user is employed in some fashion to heat ambient air before it is inhaled. Inlet tubes or pads are placed underneath the wearer's clothing, and as the person inhales, heated air in close proximity to the body is transported through conduit means of some sort to the person's nose and mouth. Devices utilizing the body heat in this manner have the obvious disadvantage of being able to introduce only stale air into the respiratory system of the user. In addition to the somewhat undesirable quality of the preheated air, apparatuses such as those are cumbersome and impede the normal functioning of the user. Furthermore, if the user is performing even moderately strenuous tasks, his or her oxygen requirements are substantially increased and it is doubtful that these devices are capable of providing enough sufficiently warmed air to satisfy such demand.
The principle of applying heat energy from a person's exhalations to increase temperature of incoming air is taught by U.S. Pat. No. 3,333,585 to Barghini and U.S. Pat. No. 3,814,094 to DeAngelis. Valveless mask apparatuses fit over the user's nose and mouth. As the user exhales, some of the heat energy from his expelled breath is absorbed by materials in the mask. Air to be inhaled is drawn through the mask and is warmed by the resultant transfer of heat energy. These devices suffer from the obvious disadvantage of intermingling exhaled air with inhaled air. An excess buildup of carbon dioxide within the cavity between the mask and the user's face is possible in situations where the user is required to breathe rapidly, rendering its use as a breathwarmer difficult if not impossible. Additionally, the ability of such devices to adequately warm enough quantities of air to satisfy the user's demands in extremely frigid conditions or in situations where the user is forced to breathe rapidly or heavily is highly doubtful.
U.S. Pat. No. 3,249,108 to Terman features a heating element contained in a pocket of a mask with incoming air passing through the element becoming heated by radiation. In situations in which the user is required to breathe heavily or rapidly, this device too may be inadequate to provide the needed quantities of sufficiently heated air, and there is also the potential for buildup of excess carbon dioxide that is present in other devices.